The invention relates to a method for the manufacture of an electrically charged fibrous filter, whose fibre material consists of a high molecular non-polar substance.
Such a method is known in the art and from this method it appears that charging of fibre material in an electric field to obtain a charged fibrous filter is difficult because of electric breakdown through the pores of the material. Covering the electrodes, between which the forming field strength is applied, with a semi-conducting material, admittedly offers the possibility of bringing the fibre material to a higher charged state, but at the same time has the drawback that this state is reached only after a longer period of time.
It is the object of the invention to provide for a rapid manufacture of highly charged fibre filters.